A fishy smell from the vaginal area is almost always caused by a shift in the bacteria that naturally live there, and the most common culprit is bacterial vaginosis (BV). The good news: it’s treatable, it’s incredibly common, and there are concrete steps you can take to get rid of it and keep it from coming back.
What Actually Causes the Smell
Your vagina naturally hosts a community of bacteria, mostly Lactobacillus species, that keep the environment acidic (a healthy pH sits between 3.8 and 4.5). That acidity prevents harmful bacteria from gaining a foothold. When something disrupts that balance, odor-causing bacteria multiply and start breaking down amino acids into compounds called biogenic amines, specifically putrescine, cadaverine, and trimethylamine. These are the chemicals responsible for the fishy smell.
As these bacteria grow, they raise the vaginal pH above 4.5, which makes the environment even more hospitable to them and less friendly to the protective Lactobacillus. It becomes a self-reinforcing cycle: the higher the pH climbs, the more odor-producing bacteria thrive, and the stronger the smell gets.
BV Is the Most Likely Cause
Bacterial vaginosis is the most common vaginal condition in women ages 15 to 44. It typically produces a thin, grayish-white discharge with a strong fishy odor that’s often more noticeable after sex. That post-sex spike happens because semen is alkaline, and exposure to it raises vaginal pH, which releases more of those odor-causing amines. Semen also directly promotes the growth of pathogenic bacteria while inhibiting the protective Lactobacillus.
BV is not a sexually transmitted infection, though sexual activity can trigger it. Many people develop BV without any clear cause.
Other Possible Causes
Trichomoniasis, a sexually transmitted infection caused by a parasite, can also produce a fishy odor with a clear or white discharge. It tends to push vaginal pH even higher, sometimes to 5.0 or above. Trichomoniasis often comes with itching, burning during urination, and irritation that BV typically doesn’t cause. If you have those additional symptoms, testing for trichomoniasis is worth asking about.
A yeast infection, by contrast, usually does not cause a fishy smell. It produces a thick, white, cottage cheese-like discharge and intense itching, but the vaginal pH typically stays normal around 4.0. If your main concern is odor rather than itching, a yeast infection is unlikely.
How to Treat It
If you’re experiencing a persistent fishy odor, the most reliable path is getting tested. A healthcare provider can diagnose BV quickly using a combination of discharge appearance, pH measurement, and microscopic examination. Treatment is straightforward: a course of antibiotics, typically taken for five to seven days, clears the infection for most people.
For recurrent BV, where the smell keeps coming back after treatment, boric acid suppositories have shown strong results. In one clinical study, vaginal odor prevalence dropped from 92.3% to 1.9% after a 14-day course of 600 mg boric acid suppositories used at bedtime. The treatment also restored healthy bacterial scores in nearly 89% of participants. Boric acid suppositories are available over the counter, but they’re best used under guidance from a provider, especially if you’re not certain of your diagnosis.
What You Can Do at Home
Several habits directly affect your vaginal bacterial balance and can help resolve mild odor or prevent it from returning after treatment.
- Stop douching. Douching increases the risk of BV by about 21%, according to longitudinal research. Commercial douche products contain fragrances, acids, and surfactants that strip away protective bacteria and irritate mucosal tissue, making the environment more vulnerable to the exact bacteria that cause odor. Your vagina is self-cleaning. Warm water on the external area is all you need.
- Avoid scented products near the vulva. Scented soaps, body washes, sprays, and wipes can disrupt vaginal pH the same way douching does. Stick to unscented, gentle cleansers for the external skin only.
- Wear breathable underwear. Cotton underwear and loose-fitting clothing reduce moisture buildup, which helps maintain the acidic environment that keeps odor-causing bacteria in check.
- Consider probiotics. Oral probiotics containing Lactobacillus rhamnosus GR-1 and Lactobacillus reuteri RC-14, the two most studied strains for vaginal health, have been shown to improve vaginal flora in BV patients. These are taken by mouth, not inserted vaginally, and work by colonizing the vaginal environment through the gastrointestinal tract.
- Use condoms when possible. Since semen directly raises vaginal pH and promotes pathogenic bacterial growth, barrier methods can help maintain your natural balance, particularly if you notice the smell worsens after unprotected sex.
When the Smell Keeps Coming Back
Recurrent BV is frustratingly common. Some people go through multiple rounds of antibiotics only to have symptoms return within a few months. This happens because antibiotics kill the overgrown bacteria but don’t always restore the Lactobacillus population needed to keep pH low and prevent recolonization.
A combined approach tends to work better for recurrent cases: antibiotics to clear the active infection, followed by boric acid suppositories or probiotics (or both) to help rebuild and maintain the protective bacterial environment. Some providers recommend extended or periodic maintenance treatments to break the cycle. If you’ve been treated more than twice in a year, it’s worth having a specific conversation about a long-term prevention plan rather than just treating each episode as it comes.
What a Normal Vagina Smells Like
Every vagina has a scent, and it changes throughout your menstrual cycle, after exercise, and with diet. A mild, slightly tangy or musky smell is completely normal and reflects the healthy acidic environment maintained by Lactobacillus bacteria. The smell you’re looking to address is specifically a strong, fishy odor, particularly one that comes with discharge changes or worsens after sex. If what you’re noticing is simply a natural scent that isn’t fishy, foul, or accompanied by unusual discharge, there’s likely nothing to treat.